Fumiyuki Nakashio

Role of surfactants in the behavior of emulsion liquid membranes. Development of new surfactants

Abstract Surfactants play an important role in the emulsion liquid membrane (henceforth ELM) process. However, only two commercial surfactants have been used so far, Span 80 and polyamine. Relatively little attention has been spent in searching for other suitable surfactants. In order to develop new surfactants for the ELM process, in this study a series of derivatives of glutamic acid dialkyl esters and dialkyl-type quaternary ammonium salts were synthesized. Copper extraction by ELM was carried out in a stirred cell using these surfactants. It was found that glutamic acid dioleyl ester was a more suitable surfactant for the ELM process than Span 80 and polyamine as regards break-up, swelling and demulsification of the W/O emulsion, and enrichment of copper.

Extraction Behavior of Hemoglobin Using Reversed Micelles by Dioleyl Phosphoric Acid

A new surfactant, dioleyl phosphoric acid (DOLPA), has been applied to the extraction of hemoglobin using reversed micelles. The reversed micelles formed by DOLPA can easily extract hemoglobin from aqueous to reversed micellar solutions. DOLPA is the first surfactant to extract hemoglobin completely without using any cosurfactants. On the basis of the difference between DOLPA and AOT reversed micelles in the forward extraction behavior of hemoglobin, the nature of the interfacial complex that would be formed between surfactants and hemoglobin at the oil−water interface was found to be the dominant factor in determining the extraction efficiency of hemoglobin by reversed micelles. In addition, back‐transfer studies of hemoglobin from the DOLPA reversed micelles were also carried out by the phase transfer method. It was found that hemoglobin, once dissolved into the DOLPA reversed micelles, is not transferred to a fresh aqueous solution even when the conditions are adjusted to not allow the forward transfer of hemoglobin. However, the addition of several kinds of alcohol drastically improved the yield in the back‐transfer of hemoglobin. The efficiency in the back‐transfer of hemoglobin strongly depends on the aqueous conditions that are in contact with the reversed micelles, such as pH, ionic strength, and alcohol concentration. A pH higher than the pI of hemoglobin, a salt concentration lower than that of the water pool, and the proper concentration of alcohol are required for the recovery aqueous phase to ensure the back‐transfer of hemoglobin from the DOLPA reversed micelles.

Extraction of lactic acid from fermented broth with microporous hollow fiber membranes

Non-dispersive solvent extraction of lactic acid based on anion-exchange reaction with tri-n-octylmethylammonium chloride dissolved in oleyl alcohol, the optimum extraction reagents selected for extractive fermentation of lactic acid with Lactobacillus rhamnosus, was attempted in a microporous hollow fiber membrane device. A satisfactory recovery of lactic acid from both aqueous solution and actual fermented broth was accomplished, signifying the great potential of integrating the membrane extraction with fermentation process. A theoretical model which took into account the mass transfer resistances across organic and aqueous films and membrane was developed to analyze and predict the extraction behavior. The model prediction was found to be in good agreement with the experimentally observed results.

Effect of coexisting alkaline metal ions on the extraction selectivity of lanthanide ions with calixarene car☐ylate derivatives

Abstract Extraction behavior of nine types of trivalent lanthanide ions from three types of aqueous solutions containing an alkaline metal ion such as lithium, sodium or potassium ion into chloroform was investigated with three types of extractants: 37, 38, 39, 40, 41, 42-hexakis(car☐ymethoxy)-5, 11, 17, 23, 29, 35-hexakis(1, 1, 3, 3-tetramethylbutyl)calix[6]arene and the cone conformational type of 25, 26, 27, 28-tetrakis(car☐ymethoxy)-5, 11, 17, 23-tetrakis(1, 1, 3, 3-tetramethylbutyl)calix[4]arene as well as p-(1, 1, 3, 3-tetrametylbutyl)phenoxyacetic acid as the monomeric analog of their calixarene derivatives. The uptake behaviors of the three types of coexisting alkaline metal ions with the calix[4]arene car☐ylate derivative and the monomeric analog were also investigated by measuring the chemical shifts of proton NMR spectra. It was found that the calix[4]arene derivative selectively extracted sodium ions, while lithium and potassium ions were hardly extracted, and also found that when sodium ion is contained in the feed solution, the order of extraction selectivity for rare earth metal ions with the calix[4]arene derivative was much changed from an ordinary system containing no sodium ion. That is, in the absence of sodium ion, the calix[4]arene derivative preferentially extracted the light lanthanides with greater ionic radii while in the presence of sodium ion it extracts the heavy lanthanides with smaller ionic radii. It was suggested that the cyclic tetramer preferentially extracts sodium ion at first and then the sodium-loaded calix[4]arene extract lanthanide ions, as a “preorganized” extractant.

Novel preparation method for surfactant-lipase complexes utilizing water in oil emulsions

A novel preparation method for surfactant-lipase complexes has been developed utilizing water in oil emulsions. In order to optimize the preparation conditions, we have investigated the effects of several operational parameters on the enzymatic activity of the surfactant-lipase complexes in organic media. When a nonionic surfactant was employed under optimal preparation conditions [alkaline pH 8-10, organic/aqueous = 90/10 (v/v), concentration of surfactant, 10 mM[, the surfactant-lipase complex efficiently catalyzed the esterification of benzyl alcohol with lauric acid in organic media. The esterification rate of the surfactant-lipase complex was increased over 16-fold relative to the native powder lipase. Furthermore, the lipase complex showed high storage stability. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 455-460, 1997.

Extraction kinetics of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester using a hollow fiber membrane extractor

A kinetic study concerning chemical complexation-based solvent extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester dissolved as an extractant in n-heptane was carried out using a microporous hydrophobic hollow fiber membrane extractor. The effects of concentration of chemical species in aqueous and organic feed solutions on the apparent permeabilities of metal species for extraction and stripping, respectively, were investigated to clarify the permeation mechanism. From the experimental results it was predicted that the permeation rate is controlled by diffusion of the chemical species in aqueous and organic phases and by interfacial chemical reaction. The experimental data were analyzed by the diffusion model accompanied with an interfacial reaction, taking into account the velocity distributions of the aqueous and organic phases through the inner and outer sides of the hollow fiber.

Effect of new surfactants on zinc extraction with liquid surfactant membranes

Abstract Using newly synthesized surfactants, extraction of zinc ion with liquid surfactant membranes (LSMs) containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester ( PC-88A) as a carrier was carried out in a stirred cell. The adsorption properties of surfactants were clarified and the effects of new surfactants on zinc extraction by LSMs were studied. New surfactants having two oleyl chains form stable emulsions in an even lower concentration range than the commercial surfactants. The extraction rate of zinc by LSMs was explained by an interfacial reaction model between the carrier and zinc ion taking into account the adsorption of a surfactant at the interface. Additionally, it is found that the new cationic surfactants appeared to accelerate the extraction rate due to an electrostatic interaction with the carrier.

Enzymatic polymerization catalyzed by surfactant-coated lipases in organic media

Structural ring-opening of lactones driven by enzymatic polymerization has been performed using low concentration dosages of surfactant-coated lipases in organic media. By comparison, enzymatic polymerization rate with coated lipase proceeded at a rate 100-fold better than native powder. Similarly a higher polymeric molecular weight (21,300), narrow dispersity (Mw/Mn=1.9) and better conversion (100%) were obtained following polyesterification tests with surfactant-coated lipase.

Extraction of rare-earth metals by liquid surfactant membranes containing a novel cyclic carrier

Abstract Extraction behavior of three rare-earth metals (Ho, Er and Y), was systematically studied by liquid surfactant membranes (LSMs) containing a novel host compound, a calixarene carboxyl derivative, which is a cyclic compound connected to some phenol rings, as a mobile carrier in a stirred cell. Using the host compound, the extraction equilibrium of the metals in liquid-liquid extraction was also investigated in order to elucidate the complexation mechanism between the metal ions and the cyclic compound. The calixarene carboxyl derivative showed a high extractability for all rare-earth metal ions compared with the analog monomer compound. The extractability for the rare-earth metals was found to increase in the following order: monomer

Hydrolysis of triolein by lipase in a hollow fiber reactor

Abstract Hydrolysis of triolein by lipase was carried out in a hollow fiber membrane reactor, oleic acid and glycerol being formed as products. It was found that hydrolysis of triolein by lipase in the hollow fiber reactor can be quantitatively explained by a Michaelis-Menten mechanism at the interface, together with competitive inhibition by oleic acid, diffusion of all chemical species and adsorption of lipase at the interface between the aqueous and organic phases. The reaction model could be applied to a wide range of conversions in the membrane reactor.